Kiev , Ukraine -LRB- CNN -RRB- -- Pro-Russian separatists struck two helicopters as well as a jet with portable air defense systems Wednesday in the Luhansk region of Ukraine .

A source within the Ukrainian military confirmed the statement by the `` South-East Army , '' which claims the group downed an Ukrainian Su-25 military jet and a Mi-24 helicopter .

Another Ukrainian Mi-24 helicopter was struck , also in the Luhansk region , but it is unclear as to whether that aircraft crashed .

On Sunday , a Ukrainian fighter jet was shot down in the Luhansk region , Leonid Matyuhin , the spokesman for Ukraine 's counterterrorist operation , told CNN .

The pilot managed to eject and is safe , Ukrainian state media reported .

The ongoing fighting -- sparked last year with by political crisis over whether Ukraine would seek closer ties with Europe or Russia -- has left more than 2,000 people dead and just under 5,000 wounded in eastern Ukraine since mid-April , according to estimates from U.N. officials .

The United States and the European Union have applied steadily increasing sanctions against Russian officials , banks and other interests since March , when Russia annexed the Black Sea Ukrainian peninsula of Crimea .

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Russia 's move came a month after Ukraine 's parliament ousted pro-Moscow President Viktor Yanukovych .

Yanukovych left office after violent protests against his government in the capital , Kiev .

Those protests were motivated in part by his decision to back out of a trade deal with the European Union in favor of closer ties with Russia .

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CNN 's Lindsay Isaac reported from Kiev . CNN 's Jason Hanna wrote from Atlanta . CNN 's Victoria Butenko and Joshua Berlinger contributed to this report .

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NEW : Pro-Russian separatists hit two helicopters , Ukranian military confirms

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NEW : A Ukranian military jet also was struck on Wednesday

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Another Ukrainian fighter jet was shot down on Sunday

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Ukraine continues a battle with pro-Russian rebels in the country 's east